Both scenarios are possible with Shimano’s latest XT Di2 Linkglide electronic drivetrain, specifically designed for e-bikes. The group was announced at Eurobike last year, but it’s only now starting to appear on some bikes. I was able to spend two days trying out the system, enough time to understand how well the concept was executed and what aspects are most relevant to mountain bikers.
The basics
As I mentioned, the new XT Di2 drivetrain is only compatible with e-bikes with the Shimano 600 or EP801 motor. It’s powered by the same battery that provides pedal assist, which means there’s no need to charge a separate battery…but that also means it’s not wireless.
The system can be configured in four different ways.
Fully manual shifting It’s exactly what it sounds like – the system only changes gears when one of the gear levers is pressed.
Fully manual shifting with Free Shift activated allows for coasting shifting – the motor spins the chainring forward while the cranks remain stationary, and the derailleur shifts along with it, allowing you to select the ideal gear for an upcoming change in terrain without having to pedal.
In the automatic shifting in freewheel modemanual shifting is necessary when the cranks are spinning, but the automatic shifting system takes over when they are stationary and the bike is in motion.
Fully automatic mode puts the computer into charge, and the derailleur will shift to the appropriate gear based on information gathered from the motor sensors. Things like cadence and speed are taken into consideration, and the algorithm decides when to change gears. There is a decent amount of customization available in this mode which is designed to help riders get the automatic shifting to match their preferred pedaling style.
To add an extra layer of confusion, there are two versions of the drivetrain, XT Di2 Hyperglide+ and XT Di2 Linkglide. Hyperglide+ is the lightest option, based on a 12-speed, 10-51t cassette. It lacks the fully automatic shifting option, although it can be configured to shift automatically while a cyclist is riding, and manual shifting while coasting is also possible.
Fully automatic shifting while pedaling and coasting is only available with the Linkglide drivetrain, which uses an 11-speed, 11-50t cassette.
Facility
One of the biggest hurdles the system faces is the amount of experimentation needed to customize it for each rider. I can see that the setup process is daunting for a beginner, who also happens to be the type of rider who would be most likely to use the fully automatic setup.
The Shimano app allows two different settings to be adjusted: shift time and uphill response. The timing of changes adjusts when the computer decides to make a change. Riders choose a numbered setting between 50 and 100 (Shimano says 72 is a good starting point), then adjust accordingly based on how responsive it feels on the trail. This number is not directly correlated to frame rate, but the higher the number, the faster the frame rate will be.
The uphill response sets the torque threshold for a gear change. Basically, if you push hard on the pedals, like you would when going uphill, the transmission will shift into an easier gear. Choosing a higher number (there are 5 levels) for the uphill response will create more time before the shift to an easier gear is initiated. It’s worth mentioning that a sudden slap on the pedals, like what would happen if you sprint out of a starting gate, would make it want to shift into an easier gear. This isn’t exactly the ideal scenario when trying to put in as much power as possible, so if you race or tend to sprint all over the place, then manual shifting while pedaling might be the better bet.
The final adjustment is to select a start speed. This is the speed the system switches to when a cyclist slows down. Imagine stopping at a trail intersection. What gear would you like to be in when rebooting? More than likely, this is the best choice for starter gear. This is also the speed the system is likely to be in after slowing down for a tight corner or a technical section of track.
Journey impressions
So how does it actually work? Better than I expected, to be honest, although I wouldn’t say it’s 100% perfect – I still regularly used the shifters to fine-tune gear selection when the system didn’t didn’t behave the way I wanted it to. That said, there were several instances where it was truly impressive. One particular section of the trail had a flat approach to a fairly steep rock slab, and I was able to leave the shifter alone while the derailleur moved the chain to the appropriate gear as I climbed, making the changes exactly at the time when I would have on my own. There were also times on the way down when I heard the chain shift to another sprocket, and then I was able to pedal around a bend with the bike already in the correct gear.
Even after adjusting the settings quite a bit via the app, there were still times when I found myself pedaling in a harder gear than necessary, or when the system changed at an inopportune time. More experimentation on a wider variety of terrain would be needed to fine-tune it even more – I would have to do repeated laps on the same section of track to bring it closer to the shifting experience I was looking for. As I mentioned in the configuration section, the amount of tinkering needed to really integrate it seems to be quite high.
Stepping back from the automatic part of the shifting, the actual shifting feel on the Linkglide cassette was very good, especially under load – I fully agree with Shimano’s statement that it is smoother than Hyperglide+, which already worked well under power.
I feel like Shimano created the automatic shifting algorithm, found it worked well, and is still trying to figure out where to implement it. Realistically I think electric commuter bikes are the perfect use case – I can see riders who haven’t been on a modern bike enjoying the fact that they don’t need to think about nuances shifting gears on their trip to work or the store. Shimano has done automatic shifting in this area before, but this is by far the best iteration yet.
The good news with this technology is that it’s not an all or nothing proposition. Riders who purchase an e-bike with XT Di2 will be able to decide which mode best suits their needs, rather than being locked into a single setting. Personally, full manual shifting with Free Shift is the mode I would probably use the most, and I have a feeling it’s the one that many mountain bikers would immediately appreciate – there are all sorts of trail scenarios when it is possible to change gears while coasting can be useful.
It’s going to be interesting to keep an eye on this system and see where the technology goes. Personally, I’m more curious what Shimano’s response to SRAM’s drivetrain will be, but in the meantime I guess I’ll keep myself busy playing with the thousands of different engine and shifting settings for see if I can unlock a combination that works well enough to convince me to let the computer take over and do all of displacement.
#Ride #Shimanos #Di2 #Linkglide #AutoShift #Drivetrain #Pinkbike
